Implantable medical devices (IMDs) include devices designed to be implanted into a patient or subject. Some examples of these devices include cardiac function management (CFM) devices such as implantable pacemakers and defibrillators or cardiac resynchronization therapy devices (CRTs), implantable devices with neural stimulation capability, implantable drug delivery systems, and implantable diagnostic devices.
The devices can be used to aid a physician or caregiver in patient diagnosis through internal monitoring of a patient's condition, which may include cardiac disease, or cardiomyopathy.
Congestive heart failure (HF) is a cardiac disease that causes the ventricles of the heart to have a reduced ability to contract which results in an inadequate amount of blood being pumped into circulation. Because blood is being pumped away from the lungs at a reduced rate, fluid may build up in a patient's lungs and cause difficulty in breathing. As a patient's condition worsens, the patient may develop a tendency to rest in an elevated posture to reduce the fluid buildup in his or her lungs. Some CRM devices provide electrical therapy to treat congestive heart failure.
Coronary artery disease is a cardiac disease that is commonly the underlying cause of ischemia. Ischemia occurs when blood flow to cardiac muscles decreases below the metabolic requirements of the heart. Detecting ischemia early is critical to the health of the patient and allows early initiation of treatment. Cardiac muscle cells that are ischemic are electrically irritable and may be more susceptible to abnormal heart rhythms (e.g., fibrillation). Further, ischemia impairs the pumping function of the heart. If left untreated the coronary artery disease may lead to myocardial infarction (i.e., heart attack).